Sérsic index
E820922
The Sérsic index is a parameter that characterizes how the intensity of light in a galaxy varies with radius, widely used to describe and classify galaxy surface brightness profiles.
All labels observed (2)
| Label | Occurrences |
|---|---|
| Sérsic index canonical | 1 |
| Sérsic index n | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T9793701 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Sérsic index Context triple: [Einasto density profile, relatedConcept, Sérsic index]
-
A.
Faber–Jackson relation
The Faber–Jackson relation is an empirical correlation in astronomy that links the luminosity of an elliptical galaxy to the velocity dispersion of its stars, providing a key tool for estimating galactic distances and masses.
-
B.
Einasto density profile
The Einasto density profile is a mathematical model used in astrophysics to describe how the density of dark matter and stars varies smoothly with distance from the centers of galaxies and galaxy clusters.
-
C.
Salpeter initial mass function
The Salpeter initial mass function is a foundational mathematical description in astrophysics that specifies how many stars of different masses form in a given stellar population, characterized by a power-law distribution favoring low-mass stars.
-
D.
Shapley Concentration
Shapley Concentration is one of the most massive known supercluster complexes of galaxies in the nearby universe, located in the constellation Centaurus.
-
E.
Hubble sequence
The Hubble sequence is a morphological classification scheme that organizes galaxies into categories such as ellipticals, spirals, and irregulars based on their visual appearance.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Sérsic index Target entity description: The Sérsic index is a parameter that characterizes how the intensity of light in a galaxy varies with radius, widely used to describe and classify galaxy surface brightness profiles.
-
A.
Faber–Jackson relation
The Faber–Jackson relation is an empirical correlation in astronomy that links the luminosity of an elliptical galaxy to the velocity dispersion of its stars, providing a key tool for estimating galactic distances and masses.
-
B.
Einasto density profile
The Einasto density profile is a mathematical model used in astrophysics to describe how the density of dark matter and stars varies smoothly with distance from the centers of galaxies and galaxy clusters.
-
C.
Salpeter initial mass function
The Salpeter initial mass function is a foundational mathematical description in astrophysics that specifies how many stars of different masses form in a given stellar population, characterized by a power-law distribution favoring low-mass stars.
-
D.
Shapley Concentration
Shapley Concentration is one of the most massive known supercluster complexes of galaxies in the nearby universe, located in the constellation Centaurus.
-
E.
Hubble sequence
The Hubble sequence is a morphological classification scheme that organizes galaxies into categories such as ellipticals, spirals, and irregulars based on their visual appearance.
- F. None of above. chosen
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
galaxy structural parameter
ⓘ
photometric parameter ⓘ surface brightness profile parameter ⓘ |
| appearsInEquation | I(R) = I_e * exp{-b_n[(R/R_e)^{1/n} - 1]} ⓘ |
| appliesTo | projected (2D) light distribution of galaxies ⓘ |
| characterizes |
radial variation of galaxy light intensity
ⓘ
shape of galaxy surface brightness profile ⓘ |
| commonlyUsedFor |
bulge–disk decompositions
ⓘ
disk galaxies ⓘ elliptical galaxies ⓘ |
| correlatesWith |
bulge-to-total light ratio
ⓘ
central surface brightness ⓘ effective radius ⓘ galaxy stellar mass ⓘ |
| dependsOn |
choice of photometric band
ⓘ
radial fitting range ⓘ sky background estimation ⓘ |
| describes | concentration of light in a galaxy ⓘ |
| domain | galaxy surface brightness profiles ⓘ |
| fittedUsing |
maximum likelihood methods
ⓘ
nonlinear least-squares methods ⓘ |
| hasCommonValues |
n = 1
ⓘ
n = 4 ⓘ |
| hasTypicalRange | 0.2–10 ⓘ |
| higherValueIndicates | more centrally concentrated light profile ⓘ |
| implementedIn |
GALFIT
ⓘ
GIM2D ⓘ IMFIT ⓘ |
| introducedBy | José Luis Sérsic ⓘ |
| introducedIn | 1963 ⓘ |
| lowerValueIndicates | less centrally concentrated light profile ⓘ |
| measuredFrom |
azimuthally averaged surface brightness profiles
ⓘ
two-dimensional galaxy images ⓘ |
| namedAfter | José Luis Sérsic ⓘ |
| nEquals |
1 for exponential profile
ⓘ
4 for de Vaucouleurs profile ⓘ |
| parameterOf | I(R) = I_e * exp{-b_n[(R/R_e)^{1/n} - 1]} ⓘ |
| partOf | Sérsic profile ⓘ |
| relatedTo | galaxy morphological type ⓘ |
| symbol | n ⓘ |
| usedAsProxyFor |
bulge prominence
ⓘ
galaxy concentration index ⓘ |
| usedIn |
extragalactic astronomy
ⓘ
galaxy morphology studies ⓘ galaxy structural decomposition ⓘ surface photometry ⓘ |
| usedToClassify |
early-type galaxies
ⓘ
late-type galaxies ⓘ |
| usedToDistinguish | disk-dominated galaxies from bulge-dominated galaxies ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Sérsic index Description of subject: The Sérsic index is a parameter that characterizes how the intensity of light in a galaxy varies with radius, widely used to describe and classify galaxy surface brightness profiles.
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.
linked to: Sérsic index